"With a stroke of his pen, Judge Walker has overruled the votes and values of 7 million Californians who voted for marriage as one man and one woman," said NOM president Brian Brown. "This ruling, if allowed to stand, threatens not only Prop 8 in California, but the laws in 45 other states that define marriage as one man and one woman.”

"Never in the history of America has a federal judge ruled that there is a federal constitutional right to same-sex marriage," he added. "The reason for this is simple – there isn’t.”

The lawsuit, Perry v. Schwarzenegger, was filed by two same-sex couples against Gov. Arnold Schwarzenegger and other state leaders, claiming the ban was unconstitutional.

An appeal to the 9th U.S. Circuit Court expected and could make its way to the U.S. Supreme Court -- putting the case in the ranks of other historical rulings like Roe v. Wade.

It's unclear how soon Wednesday's ruling will affect gay marriages in the state.

Closing arguments challenging Prop 8 were held in June. Since then, both supporters and opponents had eagerly awaited Judge Walker's ruling.

A majority of Californians approved Prop 8 at the polls 2008, sending a clear message they want the law to recognize only marriages between a man and a woman.

Defenders of Prop 8 said that if the judge struck the measure down, it would amount to taking away the rights of millions of California voters.

"The 7 million voters in California voted for Prop 8, they made a reasonable, legitimate public policy decision that the Constitution permits, and that the federal judge should just defer to their decision," said Jordan Lorence, an attorney for the Alliance Defense Fund.

Wednesday's ruling comes as groups in Iowa rallied for and against same sex marriage. In April 2009, the Iowa Supreme Court ruled that state could not ban same-sex marriage.

"Thirty-one states have been able to vote on marriage and every single state whether it's California or Maine have voted to protect marriage," said Brian Brown, executive director of the National Organization for Marriage.

"It's an idea and belief shared by the overwhelming majority of Americans and Iowans have the civil right to vote," he said.

Gay rights supporters claim that same-sex marriage has been great for the state.

"We've lived through a year and found our kids coming home to get married," said Caroline Jenison, executive director of One Iowa. "How exciting is that?"

For same-sex marriage to become illegal in Iowa, the legislature must pass a constitutional amendment that would then need to be approved by Iowa voters.

In California, both sides had said they will appeal the Prop 8 ruling, depending on its outcome. Currently, gay marriage is legal in five states - Connecticut, Iowa, Massachusetts, New Hampshire and Vermont, as well as the District of Columbia